JPH09193633A - L-shape channel structure body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sufficient strength with minimum reinforcement while reducing weight. SOLUTION: A structure body formed in approximately U-shaped cross section and approximately L-shape from the top view has a first rib 17 formed along the internal wall of the structure body 10, parallelly with a straight line L connecting a fixed point 15 and a load action point 16 with one end part 17a as an origin, coming in contact with an inner side wall 10b between both facing side walls 10b, 10c of approximately U-shape, and a section rib 18 formed along the internal wall of the structure body 10, almost vertically toward the other side wall 10c of the structure body 10 with one end part 17a of the first rib as an origin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure having a U-shaped cross section and an L-shaped plan view, which is preferably applied to a suspension arm for an automobile.

[0002]

2. Description of the Related Art A suspension (suspension device) having a cushioning action is provided between a body and an axle in order to absorb vibrations and shocks received from a road surface while a vehicle is running. In this type of suspension, a knuckle attached to a wheel is supported by a suspension arm so that the wheel can swing with respect to the vehicle body.

As a conventional suspension arm, a so-called A-shaped arm is widely used, and a steel plate is press-molded to form a hat-shaped cross section, and a sub-plate is welded to this (for example, Japanese Unexamined Patent Publication No. Hei 2 (1999) -58). No. 38,117), or an I-shaped cross-section (for example,
JP-A-61-282, 106) and the like are known.

[0004]

However, the former suspension arm described above requires welding for fixing the auxiliary plate, which is disadvantageous in terms of cost. In particular, when the suspension arm is made of aluminum in order to reduce the weight of the vehicle, welding of aluminum is difficult, and thus the cost disadvantage is remarkable.

Also, with respect to the latter suspension arm, it is extremely difficult to form the I-shape in one step by aluminum forging, and there is a problem that the number of steps increases and the cost increases. The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide an L-shaped channel structure capable of ensuring sufficient strength with minimum reinforcement while achieving weight reduction. To do.

[0006]

In order to achieve the above object, an L-shaped channel structure of the present invention is a structure having a substantially U-shaped cross section and a substantially L-shaped plan view. ,
One end of the opposite side walls of the substantially U-shape facing each other is in contact with the inner side wall and is formed along the inner wall of the structure in parallel with a straight line connecting the fixed point and the load acting point with the one end as a base point. And a second rib that is formed along the inner wall of the structure substantially perpendicular to the other side wall of the structure with one end of the first rib as a base point. It is characterized by having.

According to the structure of the present invention, when a load is applied to the load application point, the rigidity of the entire structure is increased by the first rib, but the stress generated in the channel cross section is applied to the second rib. concentrate. Therefore, the stress generated in the channel cross section where the rib is not formed becomes small, and sufficient strength can be secured by adjusting the width of the rib 2.

The structure of the present invention has a U-shaped cross section and a substantially L-shaped plan view, and the detailed structure is not particularly limited. Since the present invention can be applied if the main part of the cross section is U-shaped, the cross-section of the structure may be hat-shaped including U-shaped. The reason for limiting the cross-sectional shape is that it is easy to forge (forging can be done in one step).
Further, the present invention can be applied as long as the shape in a plan arrow view is substantially L-shaped, and therefore, the angles and lengths of the two L-shaped linear portions are not particularly limited. However, in order to form the first rib and the second rib, it is preferable to satisfy the following conditions. That is, as shown in FIG. 1, the length of the straight line portion is L1, L2 (L1> L2), the width of the channel is W,
When the angle formed by the two straight line portions is θ and the average value of the inner diameter and the outer diameter of the arc is R, the shape satisfies the following formula. However, θ is in the range of π / 2 <θ <π.

[0009]

[Equation 1]

In the present invention, the second rib is formed along the inner wall of the structure substantially vertically from the one end of the first rib toward the other side wall of the structure as shown in FIG. As shown, the stress generated in the channel cross section other than the rib is
This is because when it is formed vertically, it becomes the smallest. In this sense, it is preferable that the second rib is within ± 15 ° from the vertical.

The heights of the first ribs and the second ribs are not particularly limited, but it is more preferable that they are substantially equal to the plate thickness of the structure. If the heights of the first and second ribs are made significantly smaller than the plate thickness of the structure, the rigidity of the structure and the effect of stress concentration on the second ribs are reduced, and conversely the heights of the first and second ribs are decreased. This is because if the thickness is larger than the plate thickness of the structure, the forging process becomes difficult.

The structure of the present invention can be made of steel plate, cast iron, aluminum or aluminum alloy, but it is more preferably made of aluminum or aluminum alloy in order to reduce the weight. Moreover, it is preferable to form by forging. The L-shaped channel structure of the present invention is preferably applied to mechanical parts such as suspension arms for automobiles, building parts and the like.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 (A) is a plan view showing an L-shaped channel structure which is an embodiment of the present invention, FIG. 1 (B) is the same perspective view, and FIG.
2A is a cross-sectional view taken along the line AA of FIG.
2B is a cross-sectional view taken along the line BB of FIG.
FIG. 3C is a cross-sectional view of a structure according to another embodiment, and FIG. 3 is a graph showing the relationship of generated stress with respect to the formation position of the second rib according to the present invention.

The L-shaped channel structure 10 of this embodiment has a length L ₁ as shown in the plan view of FIG.
₂ and a second straight line portion 12 having a length L ₂ intersect each other at a bent portion 13 having an angle θ, and the cross section thereof is uniformly U-shaped as shown in FIG. 2 (A). It is a structure that has a shape.
The structure 10 having such a U-shaped cross section is called a so-called channel structure, and is one bottom wall 10a in cross section.
Two side walls 10b and 10c facing each other are continuously formed, and the distance between both side walls 10b and 10c is W.

In the present embodiment, the structure 10 has a pure U-shaped cross section, but in the present invention, as shown in FIG. The present invention can also be applied to a so-called hat-shaped structure 10 which is U-shaped and in which the tips of both side walls 10b and 10c are horizontally bent outward to form a flange 14. Figure 2 (C)
The structure 10 shown in can be applied to a reinforcing member of a vehicle body panel for an automobile, for example.

As shown in FIG. 1A, in the bent portion 13, the average value of the arcs of the inner side wall 10b and the outer side wall 10c of the side walls 10b and 10c is R, Lengths L1 and L2 (L1> L2) of the first and second straight portions 11 and 12 described above, and both side walls 10b and 10
The width W of c and the angle θ formed by the two straight portions 11 and 12 are formed into a shape that satisfies the following mathematical expression.

[0017]

[Equation 2]

The structure 10 according to the present embodiment as described above.
Basically, one end is the fixed point 15 and the other end is the load acting point 16. However, it is sufficient that a part thereof includes the basic shape of the structure 10 according to the present embodiment, as in a vehicle suspension 100 described later, and both ends of the linear portions 11 and 12 are not physically cut. Tomo
One of the ends may be the fixed point 15 and the other end may be the load acting point 16.

Particularly, in the structure 10 according to this embodiment, as shown in FIGS. 1A and 1B, the first rib is formed along the inner wall of the structure 10 in order to increase the rigidity of the entire structure. 17 are provided. One end 17a of the first rib 17 is in contact with the inner side wall 10b of the opposite side walls 10b and 10c, and a straight line connecting the fixed point 15 and the load acting point 16 with the one end 17a as a base point. It is formed parallel to L. Also, the first rib 17 is
It is formed along the inner wall of the structure 10 at a height h of a substantially plate thickness t. This is because when the structure 10 is formed by forging aluminum, if the height h of the first rib 17 is significantly larger than the plate thickness t of the structure 10, the forging process becomes difficult. On the contrary, if the height h of the first rib 17 is made significantly smaller than the plate thickness t of the structure 10, the rigidity of the structure 10 becomes small.

In the structure 10 of this embodiment,
In addition to the first rib 17 described above, a second rib 18 is provided along the inner wall of the structure 10 in order to reduce stress concentration on the general cross section (a portion other than the rib) of the structure 10. . The second rib 18 has the one end 17 a of the first rib 17 as a base point, and the side wall 10 outside the structure 10.
It is formed substantially vertically toward c.

Here, the reason why the second rib 18 is set in this way is as follows. That is, the present inventors,
In order to confirm the angular dependence of the second rib 18, FIG.
Using a test piece made of aluminum (A6061) having the shape shown in (A), a load in the Y direction was applied to the load acting point 16, and the stress was measured over the entire structure by a strain gauge. In order to increase the reliability of the measured value due to the variation in the test conditions, the maximum stress generated in the general cross section other than the second rib 18 is divided by the maximum stress generated in the structure,
This value was measured for each angle of the second rib 18 (interval of 5 °). The horizontal axis shown in FIG. 3 is the angle of the second rib 18,
As shown in the figure, the angle is centered on the base point 17a.
From the results shown in FIG. 3, it is understood that the stress generated in the general cross section other than the second rib 18 is the smallest when the second rib 18 is formed vertically, and is most preferable for relaxing the stress. In this sense, the second rib 18 is ± 1 from the vertical.
It can be said that it is preferably within 5 °.

The second rib 18 is also formed along the inner wall of the structure 10 at a height h of a substantially plate thickness t, like the first rib 17. This is because when the structure 10 is formed by forging aluminum, the second rib 1
This is because if the height h of 8 is significantly larger than the plate thickness t of the structure 10, the forging process becomes difficult. On the contrary, if the height h of the second rib 18 is made significantly smaller than the plate thickness t of the structure 10, the effect of stress concentration on the second rib 18 becomes small, and stress is concentrated on the general cross section of the structure 18. This is because there is a risk.

As Example 1, an aluminum (A6061) test piece having such a shape was prepared and subjected to a static strength test. Further, as Comparative Example 1, a structure without the first and second ribs 17 and 18, as Comparative Example 2, a structure having only the first ribs 17, and as Comparative Example 3, first and second ribs 17 are provided. , 18 is formed, but the angle of the second rib 18 is −30 °. As Comparative Example 4, the first and second ribs 17, 18 are formed but the second rib 18 is Structure with an angle of + 30 °, Comparative Example 5
As the above, a structure having two ribs formed at positions different from the above positions was prepared, and the same static strength test was performed.
The static strength test was performed by applying a load in the Y direction to the load acting point 16 and measuring the stress with a strain gauge. Table 1 shows the results. From this, it is understood that the maximum stress of Example 1 is equal to or less than that of Comparative Examples 1 to 5, but the stress of the cross section other than the rib is obviously small.

[0024]

[Table 1]

As described above, the structure 10 according to the present embodiment.
According to the above, when a load acts on the load acting point 16, the rigidity of the entire structure is increased by the first ribs 17. Also, the stress is concentrated on the second rib 18 and can be received by the second rib 18. Therefore,
Stress concentration is eliminated in the section of the general channel section having a low rigidity where the second rib 18 is not formed, and the structure 10
The load bearing capacity of is improved.

Embodiment 2 Next, an embodiment in which the above-described structure 10 of the present invention is applied to a vehicle suspension arm 100 will be described. FIG. 4 is a perspective view showing an embodiment in which the L-shaped channel structure 10 of the present invention is applied to a vehicle suspension arm 100, which is a so-called A-type suspension arm. The base ends 111 and 112 of the bifurcated arm 110 are fixed to a vehicle body of an automobile through bushes, respectively, and the tip end 113 is swingably attached to a knuckle of a wheel through a joint such as a ball joint. Therefore, in the vehicle suspension arm 100 according to the present embodiment, one base end 11 of the bifurcated arm 110 is included.
1 becomes the fixed point 15 of the structure 10 described above, and the bifurcated arm 1
The tip 113 of 10 serves as the load acting point 16 of the structure 10, and the structure 10 of the present invention is applied to the range between the base end 111 and the tip 113 on one side.

The suspension arm 100 has a substantially U-shaped cross section as shown in FIG. 2 (A) or (C).
Then, the above-mentioned first rib 17 has one end portion 17a thereof.
Of the opposite side walls 10b, 10c, the inner side wall 1
It is formed in parallel with a straight line connecting the fixed point 15 and the load acting point 16 with the one end 17a as a base point. Further, the first rib 17 is formed along the inner wall of the suspension arm 100 with a height of a substantially plate thickness. The second rib 18 is one end portion 1 of the first rib 17.
7a as a base point, and is formed substantially vertically toward the side wall 10c on the outer side of the suspension arm 100, and like the first rib 17, is formed to have a substantially plate height along the inner wall of the suspension arm 10. .

The automotive suspension arm 100 having such a shape is hot forged with a bent round bar of aluminum (A6061) in one step, and then subjected to T6 heat treatment.
It was manufactured by machining. The plate thickness is 3 mm and the weight is 0.
It was 54 kg. This is Example 2.

As a comparative example of Example 2, a suspension arm having the same shape except that the first rib 17 and the second rib 18 were not formed was manufactured by press-forming a steel plate. The plate thickness was 2.6 mm and the weight was 1.1 kg. This is referred to as Comparative Example 6. Using the suspension arm of Example 2 and the suspension arm of Comparative Example 6, first, a load was applied to the load acting point 16 to measure the strength. The result is shown in FIG. The suspension arm for automobiles is generally required not to be deformed even when a load of 500 kgf is applied, but the suspension arm of the second embodiment is 640 k.
There is no deformation even if a load is applied up to gf, which satisfies this requirement sufficiently. Further, although the rigidity is shown by the slope of the curve in FIG. 5, the suspension arm of Example 2 has the same rigidity as that of Comparative Example 6.

Then, a load of 500 kgf was applied to the load acting point 16, and the stress was measured over the entire suspension arm by a strain gauge. The measurement point is the load action point 1
6, the vicinity P1 of the first rib 17, the vicinity P2 of the first rib 17, both sides P3 and P4 of the second rib 18, and P5 immediately above the second rib 18. The results are shown in Table 2. From this, it is understood that in the suspension arm of the second embodiment, stress concentrates on the second ribs 18 and other stresses are smaller than those of the comparative example 6.

[0031]

[Table 2]

The present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the present invention.

[0033]

As described above, according to the present invention, when a load acts on the load acting point, the rigidity of the entire structure is increased by the first ribs, and the stress generated in the channel cross section is Since the ribs can be concentrated on the second rib, the stress generated in the channel portion where the rib is not formed is reduced. By adjusting the width of the rib 2, it is possible to secure sufficient strength with minimum reinforcement while achieving weight reduction. Further, since a complicated structure and welding as in the conventional case are unnecessary, even aluminum can be easily manufactured.

[Brief description of the drawings]

FIG. 1 (A) is a plan view showing an L-shaped channel structure according to an embodiment of the present invention, and FIG. 1 (B) is a perspective view thereof.

2A is a sectional view taken along line AA of FIG. 1A, FIG. 2B is a sectional view taken along line BB of FIG. 1A,
FIG. 6C is a cross-sectional view of a structure according to another embodiment.

FIG. 3 is a graph showing a relationship of generated stress with respect to a formation position of a second rib according to the present invention.

FIG. 4 is a perspective view showing an embodiment in which the L-shaped channel structure of the present invention is applied to a vehicle suspension arm.

FIG. 5 is a graph showing a load-stroke curve when a load is applied to the vehicle suspension arm shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Structural body 10a ... Bottom wall 10b, 10c ... Side wall 11, 12 ... Straight part 13 ... Bending part 15 ... Fixing point 16 ... Load acting point 17 ... First rib 18 ... Second rib 100 ... Automotive suspension arm

Claims (4)

[Claims] 1. A structure having a substantially U-shaped cross section and a substantially L-shaped plan view, one end of which is in contact with an inner side wall of opposite side walls of the substantially U-shape, A first rib formed along the inner wall of the structure in parallel with a straight line connecting the fixed point and the load acting point with the one end as a base point, and the structure with the one end of the first rib as a base point An L-shaped channel structure having a second rib formed along the inner wall of the structure substantially perpendicular to the other side wall of the body. 2. The L-shaped channel structure according to claim 1, wherein the heights of the first ribs and the second ribs are substantially equal to the plate thickness of the structure. 3. The L-shaped channel structure according to claim 1, which is made of aluminum or an aluminum alloy. 4. An automobile suspension arm comprising the L-shaped channel structure according to any one of claims 1 to 3.